1. Field of the Invention
The present invention relates to waterproofing processes and materials, and in particular a sheet laminated with non-hydrated granular bentonite for applications for waterproofing.
2. Description of the Prior Art
Various bentonite type waterproofing panels have been advanced in the past. In particular, American Colloid Company, of Skokie, Illinois has obtained numerous patents on various water barrier panels, but they all have limitations in use. Generally speaking, these panels are easily damaged, and lose their ability to function if not handled carefully. A typical water barrier panel is shown in U.S. Pat. No. 4,048,373 which comprises two opposing spaced sheets using a sealing composition between the sheets that has bentonite in it, with a water soluble dispersing agent. This type of a panel is used against a foundation to act as a water barrier shielding the foundation, and is essentially a corrugated paper board carrier filled with finely granulated bentonite. This patent does describe the well-known waterproofing characteristics of bentonite, but the structure disclosed fails to provide the durability and adaptability of the present device.
U.S. Pat. No. 4,048,373 is a continuation in part of U.S. Pat. No 3,949,560 which includes substantially the same disclosure, and a divisional patent U.S. Pat. No. 4,103,499 also shows the same type of a water barrier panel. Related U.S. patents, from the same family of applications, include U.S. Pat. Nos. 4,021,402 and 4,l39,588.
American Colloid Company also has two additional related U.S. Pat. Nos. 4,126,543 and 4,194,970 which show a method of screening bentonite material for use in obtaining correct size bentonite particles. These patents do not show waterproofing panels as such.
U.S. Pat. No. 3,186,896 shows a facing sheet quite similar to that described in the prior patents, comprising a barrier panel made of corrugated paper board that is filled with bentonite.
U.S. Pat. No. 4,084,382 relates to a method for containing water having a high concentration of water soluble industrial wastes to reduce the likelihood of the wastes destroying the bentonite used. The bentonite is mixed with a water soluble dispersing agent and a water soluble polymer in a particular ratio to form a sealing compound.
U.S. Pat. No. 3,466,827 shows a roof panel that is formed to provide impervious construction, and is a self-sealing panel using a finely divided soluble bentonite clay in a layer.
U.S. Pat. No. 4,070,839 shows a moisture impervious panel that has a pair of spacing sheets interconnected by a central rigid support sheet, such as corrugated fiberglass. The corrugated sheet forms long pockets filled with a composition of bentonite and a compressed filler such as vermiculite. This construction forms a very rigid panel that is not usable in any form other than smaller sheets, and does not have sufficient flexibility to accommodate any substantial shifting of the surfaces that the panels are covering.
U.S Pat. No. 4,467,015 shows another type of structure that has two layers, and which can be formed into a roll. Each layer includes a sheet of water permeable material and a coating of dry particles of bentonite on one surface of the sheet. An adhesive is used for applying the particles of bentonite to the water permeable material, and the bentonite particles are placed so that they face the surface of the structure that is to be waterproofed. The sheet shown in U.S. Pat. No. 4,467,015 has inherent problems with the cardboard or water permeable sheet, namely migration of water and leaking at the joints until the material attempts to self-seal. The material also is susceptible to rain damage and it needs protection against the weather when installed, until it is covered by backfilling or the like.
U.S. Pat. No. 3,676,198 shows apparatus for entraining bentonite particles in an air stream, and intermixing the particles with a coating material to cause the mixture to adhere in a layer onto a wall surface 11, and provide for a waterproofing layer in that manner. The patent requires special on site installation equipment.
U.S. Pat. No. 4,534,926 shows an uninhibited bentonite composition which comprises an intimate mixture of bentonite clay with polypropene, polybutene or mixtures thereof. The material is capable of being extruded through an extrusion die and further a sheet like material can be put between two release papers, but still has to be formed through an extrusion die that has a wide opening to form a type of sheet.
Thus, while the prior art shows various attempts at forming panels that use bentonite for waterproofing, and even though the desirable properties of bentonite for waterproofing have been known, the problems remain in obtaining a waterproofing sheet that is easily used; that withstands weathering; that seals leaks and seals well at joints and will continue to provide waterproofing over a span of time.